Warren, who gained international fame for his bestseller, "The Purpose Driven Life," remembered his son as "an incredibly kind, gentle, and compassionate man."

"But only those closest knew that he struggled from birth with mental illness, dark holes of depression, and even suicidal thoughts. In spite of America's best doctors, meds, counselors and prayers for healing, the torture of mental illness never subsided," Warren wrote in the letter to the Saddleback congregation.

After a "fun evening" as a family, Warren said his son took his life "in a momentary wave of despair at his home."

Warren said he marveled at his son's courage to keep on living in his darkest moments despite his pain.

"I'll never forget how, many years ago, after another approach had failed to give relief, Matthew said, 'Dad, I know I'm going to heaven. Why can't I just die and end this pain?'" Warren wrote. "But he kept going for another decade.

Warren, one of the best-known pastors in the world, grew his Saddleback Church from humble beginnings into a powerhouse ministry.

The church started as a dream for "a place where the hurting, the depressed, the confused can find love, acceptance, help, hope, forgiveness and encouragement," according to the Saddleback Church website.

Since Warren's first public service on Easter Sunday in 1980, Saddleback Church has grown tremendously with more than 200 ministries.

His 1995 book, "The Purpose Driven Church," Warren shared the principles that led to the success of Saddleback.

His follow-up book in 2002, "The Purpose Driven Life," catapulted him into the world spotlight.

"The history of this idea -- 'purpose driven' -- is not something I thought up in the first place," Warren told ABC News in 2007. "There have been hundreds of books throughout history that talked about worship, fellowship, discipleship, ministry and evangelism."

The book was a hit and was been translated into dozens of languages and has sold tens of millions of copies.